Lithium secondary battery electrolytic solution and secondary battery including said electrolytic solution

Abstract

A new electrolytic solution system for lithium secondary batteries. Provided is a lithium secondary battery electrolytic solution containing a nonaqueous solvent and a lithium salt. The nonaqueous solvent is mixed at an amount of not more than 3 mol with respect to 1 mol of the lithium salt.

The invention claimed is: 
     
       1. A secondary battery comprising: a positive electrode including a positive electrode active material; a negative electrode including a negative electrode active material capable of occluding and releasing lithium ions; and an electrolytic solution for lithium secondary batteries
 wherein the electrolytic solution comprising a nonaqueous solvent and a lithium salt, wherein the nonaqueous solvent is mixed at an amount of not more than 3 mol with respect to 1 mol of the lithium salt; and 
 the positive electrode active material is oxygen; and 
 the nonaqueous solvent is acetonitrile, tetrahydrofuran, dimethyl sulfoxide, y-butyrolactone, or sulfolane. 
 
     
     
       2. The secondary battery according to  claim 1 , wherein the nonaqueous solvent is mixed at an amount of not less than 1 mol but not more than 3 mol with respect to 1 mol of the lithium salt. 
     
     
       3. The secondary battery according to  claim 2 , wherein the nonaqueous solvent is mixed at an amount of not less than 1.5 mol but not more than 2.5 mol with respect to 1 mol of the lithium salt. 
     
     
       4. The secondary battery according to  claim 1 , wherein the lithium salt is lithium bis(trifluoromethanesulfonyl)amide (Li[N(CF 3 SO 2 ) 2 ]), lithium bis(perfluoroethylsulfonyl)amide (Li[N(C 2 F 5 SO 2 ) 2 ]), or lithium bis(fluorosulfonyl)amide (LiN(SO 2 F) 2 ). 
     
     
       5. The secondary battery according to  claim 1 , wherein the nonaqueous solvent is an aprotic solvent. 
     
     
       6. The secondary battery according to  claim 1 , wherein the negative electrode active material is a carbon material. 
     
     
       7. The secondary battery according to  claim 6 , wherein the carbon material is graphite. 
     
     
       8. The secondary battery according to  claim 1 , wherein the negative electrode active material is metal lithium or a lithium alloy. 
     
     
       9. The secondary battery according to  claim 1 , wherein the negative electrode active material is a carbon material; and the nonaqueous solvent is acetonitrile, tetrahydrofuran, dimethyl sulfoxide, γ-butyrolactone, or sulfolane. 
     
     
       10. The secondary battery according to  claim 1 , wherein the negative electrode active material is a carbon material; and the lithium salt is lithium bis(trifluoromethanesulfonyl)amide (Li[N(CF 3 SO 2 ) 2 ]), lithium bis(perfluoroethylsulfonyl)amide (Li[N(C 2 F 5 SO 2 ) 2 ]), or lithium bis(fluorosulfonyl)amide (LiN(SO 2 F) 2 ). 
     
     
       11. The secondary battery according to  claim 1 , wherein the lithium salt is lithium bis(trifluoromethanesulfonyl)amide (Li[N(CF 3 SO 2 ) 2 ]), lithium bis(perfluoroethylsulfonyl)amide (Li[N(C 2 F 5 SO 2 ) 2 ]), or lithium bis(fluorosulfonyl)amide (LiN(SO 2 F) 2 ); and the nonaqueous solvent is acetonitrile, tetrahydrofuran, dimethyl sulfoxide, γ-butyrolactone, or sulfolane. 
     
     
       12. The secondary battery according to  claim 1 , wherein the negative electrode active material is a carbon material; the nonaqueous solvent is acetonitrile, tetrahydrofuran, dimethyl sulfoxide, γ-butyrolactone, or sulfolane; and the lithium salt is lithium bis(trifluoromethanesulfonyl)amide (Li[N(CF 3 SO 2 ) 2 ]), lithium bis(perfluoroethylsulfonyl)amide (Li[N(C 2 F 5 SO 2 ) 2 ]), or lithium bis(fluorosulfonyl)amide (LiN(SO 2 F) 2 ). 
     
     
       13. The secondary battery according to  claim 12 , wherein the carbon material is graphite. 
     
     
       14. The secondary battery according to  claim 1 , wherein the negative electrode active material is a metal lithium or a lithium alloy; and the nonaqueous solvent is acetonitrile, tetrahydrofuran, dimethyl sulfoxide, γ-butyrolactone, or sulfolane. 
     
     
       15. The secondary battery according to  claim 1 , wherein the negative electrode active material is a metal lithium or a lithium alloy; and the lithium salt is lithium bis(trifluoromethanesulfonyl)amide (Li[N(CF 3 SO 2 ) 2 ]), lithium bis(perfluoroethylsulfonyl)amide (Li[N(C 2 F 5 SO 2 ) 2 ]), or lithium bis(fluorosulfonyl)amide (LiN(SO 2 F) 2 ).